core: Make atomic methods public
core::rt: Implement SharedChan
core::rt: Add SharedPort
core::rt: Add `MegaPipe`, an unbounded, multiple producer/consumer, lock-free queue
std: Fix stage0 build
std::rt: Use AtomicUint instead of intrinsics in comm
std::rt: Destroy the task start closure while in task context
std::rt: Remove in incorrect assert